The present invention relates to an engine control method for an electronic-type engine control system, or more in particular to an engine control method capable of dampening the longitudinal oscillation of a vehicle such as an automobile under acceleration.
The driver and passengers feel uncomfortable when the vehicle pitches or oscillates in the longitudinal directions (running directions) of the vehicle under acceleration.
Methods of preventing such a longitudinal oscillation of the vehicle by an electronic-type control system have been suggested.
In a method disclosed in JP-A-59-231144 or JP-A-60-30446, for example, compensation is made by the fuel injection during deceleration. According to a method disclosed in JP-A-59-93945, on the other hand, compensation is secured by ignition advance or fuel supply amount to minimize the torque variations during the drive at a very low speed.
The conventional methods described above, though capable of dampening the longitudinal oscillation of the vehicle during steady run or deceleration, pose the problem that effective dampening of oscillation is difficult during acceleration. This is due to the fact that means has not yet been introduced for detecting the longitudinal oscillation of the vehicle during acceleration.
Another problem of the prior art is that the ignition advance or the amount of fuel supplied is set in such a manner as to dampen gas discharge or to shift from the original value of control, and therefore the exhaust gas purification performance is deteriorated.